<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>
<body>
    <script>
var findTheDifference = function(s, t) {
    for( let letter of s ){
        t = t.replace(letter,'')
    }
    return t
};
        
s = "dbca"
t = "abcde"
console.log(findTheDifference(s,t))
    </script>
</body>
</html>